Italian marine reserve effectiveness: Does enforcement matter?

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Abstract

Marine protected areas (MPAs) have become popular tools worldwide for ecosystem conservation and fishery management. Fish assemblages can benefit from protection provided by MPAs, especially those that include fully no-take reserves. Fish response to protection can thus be used to evaluate the effectiveness of marine reserves. Most target fish are high-level predators and their overfishing may affect entire communities through trophic cascades. In the Mediterranean rocky sublittoral, marine reserves may allow fish predators of sea urchins to recover and thus whole communities to be restored from coralline barrens to macroalgae. Such direct and indirect reserve effects, however, are likely to be related to the enforcement implemented. In Italy, many MPAs that include no-take reserves have been declared, but little effort has been spent to enforce them. This is a worldwide phenomenon (although more common in some regions than others) that may cause MPAs and reserves to fail to meet their targets. We found that 3 of 15 Italian marine reserves investigated had adequate enforcement, and that patterns of recovery of target fish were related to enforcement. No responses were detected when all reserves were analyzed as a whole, suggesting enforcement as an important factor to be considered in future studies particularly to avoid that positive ecological responses in properly managed reserves can be masked by neutral/negative results in paper parks. Positive responses were observed for large piscivores (e.g. dusky groupers) and sea urchin predators at reserves where enforcement was effective. Those reserves with low or null enforcement did not differ from fished areas.

Introduction

Generally speaking, marine protected areas (MPAs) refer to portions of the coastline and/or sea where human activities, especially fishing, are restricted or banned (Agardy et al., 2003). As fish assemblages usually include many species targeted by fishing, they are primarily expected to benefit from protection within MPAs, especially those having no-take reserves (Dayton et al., 1995, Micheli et al., 2004, McClanahan et al., 2007). The evaluation of these benefits, in terms of increase in density and size of target fishes (Mosquera et al., 2000, Côté et al., 2001, Halpern, 2003, Micheli et al., 2004, Claudet et al., 2006, Guidetti and Sala, 2007), can be useful to assess the ecological effectiveness of reserves. Moreover, most target fishes are high-level predators and their functional extinction may cause community-wide changes (Sala et al., 1998, Jackson et al., 2001). Protection from fishing, therefore, may directly restore populations of target fishes and indirectly drive whole communities towards an unfished state (Sala et al., 1998, Shears and Babcock, 2002, Micheli et al., 2004, Bevilacqua et al., 2006, Guidetti, 2006). We use hereafter the term ‘ecological effectiveness’ of marine reserves to define the responses to protection from fishing encompassing direct and indirect effects.

Marine reserve studies have undoubtedly improved our understanding of the unfished state of ecosystems and target populations (Shears and Babcock, 2002, Guidetti and Sala, 2007). It is common wisdom, however, that a number of reserves do not meet their potential ecological objectives and that negative/neutral results in reserve studies are mostly underreported in the literature (Halpern and Warner, 2002). Failing reserves are attributable to causes like inappropriate design (Sala et al., 2002) or ineffective enforcement (Mora et al., 2006), which may be overlooked if negative/neutral results are not taken into account.

It is becoming increasingly recognized that a large proportion of marine reserves around the world receive ineffective enforcement. These are the so-called ‘paper parks’, where protection occurs only in theory (Mora et al., 2006). In such cases the use of proper sampling designs suggested by many authors to properly investigate reserve effectiveness (CIESM, 1999, Guidetti, 2002), e.g. by comparing replicated ‘reserve vs fished’ sites, is useless. In fact, the comparison ‘reserve vs fished’ sites makes sense only if protection really occurs. The scant information in many published studies about compliance and enforcement at the reserves investigated makes the interpretation of results uncertain. A major effort, therefore, is needed to make inferences about reserve effectiveness, paying special attention whenever data from both well-enforced and paper reserves are pooled to extract general patterns (e.g. in meta-analyses). Pooling data from enforced reserves and from paper parks carries the risk of incorrectly downplaying the importance of reserves because neutral results from paper parks could mask the positive responses of well-enforced reserves.

In the Mediterranean Sea there has been a rush in recent years to establish MPAs and reserves (Juanes, 2001). In Italy there are currently 25 MPAs formally established (with more than 20 in the process of becoming established), ranging in size from 120 to more than 50,000 hectares in total surface area. Italian MPAs include one or more no-take/no-access zones (hereafter called ‘reserves’ in the text and formally defined as ‘A zones’ according to Italian law), surrounded by buffer zones (defined as ‘B and C zones’, where restrictions to human uses, including fishing, become progressively more lax) (Villa et al., 2002).

Previous studies that investigated fish response to protection within Italian marine reserves showed (1) positive effects (Vacchi et al., 1998, Guidetti et al., 2005, Guidetti, 2006) or neutral results (Tunesi et al., 2006) on fish density and size, and (2) no obvious patterns in terms of community shifts (Sala et al., 1998, Guidetti et al., 2005, Micheli et al., 2005, Guidetti, 2006, Guidetti and Sala, 2007). As regards the community shift, two target sea breams, i.e. Diplodus sargus and Diplodus vulgaris, have been identified as the most effective predators of sea urchins, with the latter being the most important grazer in rocky reefs (Sala et al., 1998). When released from predation control, sea urchins may increase in density and overfeed on macroalgae, which in turn may cause the transition from macroalgal beds to barrens (Sala et al., 1998). Since the recovery of sea breams (and other predator fish) was observed within reserves, along with lower urchin density and less extended barrens (Guidetti and Sala, 2007), Diplodus density can be assumed to be an index of the potential of reserves to recover from barrens to algal beds or to maintain flourishing algal beds.

In spite of the increasing number of MPAs in Italy, no general evaluations have been done to assess the ecological responses to protection from fishing. A nation-wide project, named “Sistema Afrodite”, was thus started in 2002 (Greco et al., 2004), with the aim of allowing a balanced assessment of the actual effectiveness of marine reserves in the country (including potential neutral/negative results).

This paper is intended to (1) assess the effects of different levels of enforcement on the ecological effectiveness of reserves (i.e. direct and indirect effects), and (2) highlight the risk of misinterpreting analyses about the effectiveness of multiple marine reserves whenever the enforcement is not properly taken into account.

Section snippets

Sampling areas and procedures

We examined fish response to protection in 15 Italian marine reserves (Mediterranean Sea; Fig. 1) during two to four sampling campaigns (depending on the reserve) carried out at all 15 locations (i.e. each spatial unit including reserve and nearby fished sites) between May 2002 and October 2003.

Replicated visual censuses were done at several reserves and nearby fished sites at each location. We focused on fish associated with rocky reefs because (1) rocky reefs are the most common habitat

Results

Across all locations combined, total fish density was on average 1.15 times greater in reserves than in fished areas (ln R = 0.16 ± 0.17; 95% CI) (Fig. 2A). The lower the enforcement level, the less pronounced the differences: from 1.31 (ln R = 0.30 ± 0.56; 95% CI) to 1.06 (ln R = 0.06 ± 0.23; 95% CI) times greater in reserves than at fished sites at reserves where enforcement was high to low, respectively (Fig. 2A). In all cases, however, CI overlapped the zero values, which means that differences were not

Discussion

This study evaluated the consequences of different levels of enforcement on the ecological effectiveness of 15 Italian marine reserves on fish, in terms of direct effects on target fish and their potential of indirectly influencing entire rocky reef communities (Guidetti and Sala, 2007 and references therein). In addition, we demonstrated the importance of taking into account the enforcement at the reserves studied when procedures are used to summarize or generalize the effectiveness of

Acknowledgements

This study was carried out in the framework of the national research projects ‘Sistema Afrodite’ and ‘Venere’, funded by ICRAM and CoNISMa, respectively. We wish to thank Laura Verginella, Angelo Palmeri and Francesco Mura for their invaluable efforts during the field sampling at Miramare, Ustica and Tavolara, respectively, and Joachim Claudet for his useful suggestions.

References (55)

  • CIESM, 1999. Scientific design and monitoring of Mediterranean marine protected areas. Workshop Series No....
  • Clark, C.W., 1981. Fisheries resources and fishing rights. Report of the ACMRR working party on the scientific basis of...
  • J. Claudet et al.

    Assessing the effects of a marine protected area (MPA) on a reef fish assemblage in a northwestern Mediterranean marine reserve: identifying community-based indicators

    Biological Conservation

    (2006)
  • I.M. Côté et al.

    Effects of marine reserves characteristics on the protection of fish populations: a meta-analysis

    Journal of Fish Biology

    (2001)
  • P.K. Dayton et al.

    Environmental effects of marine fishing

    Aquatic Conservation: Marine and Freshwater Ecosystems

    (1995)
  • F. Dufour et al.

    Comparaison des inventaires de poissons dans les aires marines protégées de Méditerranée: influence de la surface et de l’ancienneté

    Cybium

    (2007)
  • Francour, P., 1990. Dynamique de l’écosystème àPosidonia oceanica dans le parc national de Port-Cros. Analyse des...
  • P. Francour

    Pluriannual analysis of the reserve effect on ichthyofauna in the Scandola natural reserve (Corsica, Northwestern Mediterranean)

    Oceanologica Acta

    (1994)
  • Froese, R., Pauly, D., 2006. Fish Base. World Wide Web Electronic Publication....
  • A. Friedlander et al.

    Designing effective marine protected areas in seaflower biosphere reserve, Colombia, based on biological and sociological information

    Conservation Biology

    (2003)
  • A.M. Friedlander et al.

    Contrasts in density, size, and biomass of reef fishes between the northwestern and the main Hawaiian islands: the effects of fishing down apex predators

    Marine Ecology Progress Series

    (2002)
  • J.A. Garcìa-Charton et al.

    Multi-scale spatial heterogeneity, habitat structure, and the effect of marine reserves on Western Mediterranean rocky reef fish assemblages

    Marine Biology

    (2004)
  • S. Greco et al.

    ‘Sistema Afrodite’: an integrated programme for the inventorying and monitoring of the core zones of the Italian marine protected areas

    Aquatic Conservation: Marine and Freshwater Ecosystems

    (2004)
  • P. Guidetti

    Mediterranean MPAs: the importance of experimental design in detecting the effects of protection measures on fish

    Aquatic Conservation: Marine and Freshwater Ecosystems

    (2002)
  • P. Guidetti et al.

    Protection effects on fish assemblages, and comparison of two visual-census in shallow artificial rocky habitats in the northern Adriatic Sea

    Journal of the Marine Biological Association of the United Kingdom

    (2005)
  • P. Guidetti

    Marine reserves reestablish lost predatory interactions and cause community changes in rocky reefs

    Ecological Applications

    (2006)
  • P. Guidetti et al.

    Community-wide effects of marine reserves

    Marine Ecology Progress Series

    (2007)
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